The interpretation timeline
Matthew 5:1 Douay-Rheims

And seeing the multitudes, he went up into a mountain, and when he was set down, his disciples came unto him.

A.D. 367 – 1849 12 witnesses 21 excerpts

Patristic

before A.D. 750
367
A.D.
Hilary of Poitiers Patristic
c. A.D. 310–367
“Or, He ascends the mountain, because it is placed in the loftiness of His Father’s Majesty that He gives the commands of heavenly life.”
397
A.D.
Ambrose of Milan Patristic
A.D. 339–397
“(De Officiis i. 16.) In the eye of Heaven blessedness begins there where misery begins in human estimation.”
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“(Hom. xv.) By not choosing His seat in the city, and the market place, but on a mountain in a desert, He has taught us to do nothing with ostentation, and to depart from crowds, above all when we are to be employed in philosophy, or in speaking of serious things.”
“He ascended a mountain, first, that He might fulfil the prophecy of Esaias, Get thee up into a mountain; (Is. 40:9.) secondly, to shew that as well he who teaches, as he who hears the righteousness of God should stand on an high ground of spiritual virtues; for none can abide in the valley and speak from a mountain. If thou stand on the earth, speak of the earth; if thou speak of heaven, stand in heaven. Or, He ascended into the mountain to shew that all who would learn the mysteries of the truth should go up into the Mount of the Church of which the Prophet speaks, The hill of God is a hill of fatness. (Ps. 68:15.)”
Source
“Or, He here calls all loftiness of soul and temper spirit; for as there are many humble against their will, constrained by their outward condition, they have no praise; the blessing is on those who humble themselves by their own choice. Thus He begins at once at the root, pulling up pride which is the root and source of all evil, setting up as its opposite humility as a firm foundation. If this be well laid, other virtues may be firmly built thereon; if that be sapped, whatever good yon gather upon it perishes.”
Source
420
A.D.
Jerome Patristic
c. A.D. 347–420
“Some of the less learned brethren suppose the Lord to have spoken what follows from the Mount of Olives, which is by no means the case; what went before and what follows fixes the place in Galilee. aMount Tabor. we may suppose, or any other high mountain.”
“He spoke to them sitting and not standing, for they could not have understood Him had He appeared in His own Majesty.”
430
A.D.
Augustine of Hippo Patristic
A.D. 354–430
“(de Cons. Ev. ii. 19.) Or He may be thought to have sought to shun the thickest crowd, and to have ascended the mountain that He might speak to His disciples alone.”
“(de Serm. Dom. in Mont. i. 1.) Or, He ascends the mountain to shew that the precepts of righteousness given by God through the Prophets to the Jews, who were yet under the bondage of fear, were the lesser commandments; but that by His own Son were given the greater commandments to a people which He had determined to deliver by love.”
Source
“Or, to teach sitting is the prerogative of the Master. His disciples came to him, that they who in spirit approached more nearly to keeping His commandments, should also approach Him nearest with their bodily presence.”
“(de Cons. Ev. ii. 19.) It causes a thought how it is that Matthew relates this sermon to have been delivered by the Lord sitting on the mountain; Luke, as He stood in the plain. This diversity in their accounts would lead us to think that the occasions were different. Why should not Christ repeat once more what He said before, or do once more what He had done before? Although another method of reconciling the two may occur to us; namely, that our Lord was first with His disciples alone on some more lofty peak of the mountain when He chose the twelve; that He then descended with them not from the mountain entirely, but from the top to some expanse of level ground in the side, capable of holding a great number of people; that He stood there while the crowd was gathering around Him, and after when He had sate down, then His disciples came near to Him, and so to them and in the presence of the rest of the multitude He spoke the same sermon which Matthew and Luke give, in a different manner, but with equal truth of facts.”
Source
“(de Serm. in Mont. i. 1.) Or, the phrase is introductory of an address longer than ordinary.”
“(ubi sup.) Whoever will take the trouble to examine with a pious and sober spirit, will find in this sermon a perfect code of the Christian life as far as relates to the conduct of daily life. Accordingly the Lord concludes it with the words, Every man who heareth these words of mine and doeth them, I will liken him to a wise man, & c.”
Source

Medieval

c. 750 – 1100
856
A.D.
Rabanus Maurus Medieval
c. A.D. 780–856
“Mystically, this sitting down of Christ is His incarnation; had He not taken flesh on Him, mankind could not have come unto Him.”
908
A.D.
c. A.D. 841–908
“This should be known, that the Lord had three places of retirement that we read of, the ship, the mountain, and the desert; to one of these He was wont to withdraw whenever He was pressed by the multitude.”

Scholastic

c. 1100 – 1500
1256
A.D.
Thomas Aquinas Catholic
1225–1274
“"Seeing the crowds, Jesus." Here the Lord sets forth his teaching, and this is divided into three parts. In the first is set down the teaching of Christ; in the second is set down the power of the teaching; in the third, the end to which it leads. The second is at chapter 13; the third at chapter 17. The first is divided into three. In the second, the ministers of the teaching are instructed; in the third, the adversaries are confounded. The second is at chapter 10; the third at chapter 11. The first is divided into two. In the first, the teaching of Christ is set forth; in the second, it is confirmed by miracles, at chapter 8. The first into two. In the first, a kind of title is prefixed to the teaching; in the second, the teaching itself is explained, at "Blessed are the poor in spirit." Concerning the first he does three things. First he describes the place where the teaching was set forth; second, the hearers of the teaching; third, he sets down the manner of teaching. The second at "and when he had sat down"; the third at "and opening his mouth he taught them." He says therefore — as I said, that they followed, etc. "Seeing the crowds, Jesus." This text can bear a twofold understanding. First, thus: he went up in order to teach the crowds, that is, not fleeing them. Hence Chrysostom says that just as a craftsman, when he sees the material prepared, delights to work, so the priest delights to preach when he sees the people gathered together; and therefore, "he went up"; Psalm 34:18: "I will confess to you in the great Church." Or otherwise: "he went up," namely fleeing the crowds, so as to teach the disciples more securely; Ecclesiastes 9:17: "the words of the wise are heard in silence." And it should be noted that we read that Christ had three refuges: for at times he fled to the mountain, as is said here, and John 8:1: "And Jesus went to the Mount of Olives." At other times to a boat; Luke 5:1: "when many crowds pressed upon him... going up into one boat, which was Simon's... sitting he taught." The third, into the desert; Mark 6:31: "let us go apart into the desert." And this is fitting enough; for in three things a man can have refuge in God: in the protection of the divine height, which is signified by the mountain; Psalm 124:1: "they who trust in the Lord are as Mount Zion." In ecclesiastical fellowship, which is designated by the boat; Psalm 121:3: "Jerusalem, which is built as a city, whose participation is in itself." In the solitude of religious life, which is taken through the desert, through contempt of temporal things; Hosea 2:14: "I will lead her into solitude, and I will speak to her heart"; Psalm 54:8: "behold, I have gone far off in flight, and I have remained in solitude." Now he went up onto the mountain for five reasons. The first, to show his excellence: for he himself is the mountain of which Psalm 67:16 speaks: "the mountain of God, a fat mountain." The second, to show that the teacher of this doctrine ought to ascend to the eminence of life; Isaiah 40:9: "Get you up upon a high mountain, you who bring good tidings to Zion." Chrysostom: no one can stand in the valley and speak of heaven, etc. The third reason, to show the height of the Church to which the teaching is set forth; Isaiah 2:2: "the mountain of the house of the Lord shall be on the top of mountains, and shall be exalted above the hills." Fourth, to show the perfection of this teaching, because it is most perfect; Psalm 35:7: "your justice is like the mountains of God." Fifth, so that it might correspond to the old legislation, which was given on a mountain; Exodus 19 and 24. Consequently the hearers are set down: "and when he had sat down, his disciples came to him." Two things can be noted in his sitting. Humiliation; Psalm 138:2: "you have known my sitting down." When he was in the height of the divine majesty, his teaching could not be grasped; but then men began to grasp it, when he humbled himself. Or this pertains to the dignity of the office of teacher; below, 23:2: "the Scribes and Pharisees have sat on the chair of Moses." For quiet is required for the pursuit of wisdom. "His disciples came to him," etc., not only in body but in mind; Psalm 33:6: "come to him, and be enlightened"; Deuteronomy 33:3: "they who draw near to his feet shall receive of his teaching." And note that when the Lord preached to the crowds, he stood; Luke 6:17: "Jesus, coming down from the mountain, stood in a level place"; but here, when teaching the disciples, he sat. From this arose the custom that preaching to crowds is done standing, and to religious, sitting. "And opening his mouth he taught them." Here the manner of the teaching is set down. In his saying "opening," it is signified that he had been silent for a long time before. And it shows that he was about to make a great and long sermon, as Augustine says. Or that he was about to say great and profound things; for so men are accustomed to do; Job 3:1: "after this Job opened his mouth, and cursed his day." And he says "his own mouth": for before he had opened the mouths of the prophets; Wisdom 10:21: "wisdom opened the mouth of the dumb, and made the tongues of infants eloquent": for he himself is the wisdom of the Father. But here there is a question: for this sermon is set down, as to many points, also at Luke 6:20ff. But there seems to be a contrariety between here and there, as is evident in the text. And Augustine gives two solutions. One is that this is a different sermon from that one: for he first went up onto the mountain, and delivered this sermon to the disciples, and afterward, coming down, he found the crowd gathered, to whom he preached the same things, and recapitulated many of them: and it is of this that Luke 6:20ff. speaks. Or otherwise it should be said that there was one mountain, which had a level place on its side: that level place was raised up by another, smaller hill. Hence the Lord went up onto the mountain, that is, onto the level place of that mountain. And first he went up higher, and called together the disciples, and there he chose the twelve apostles, as is evident in Luke; and afterward, coming down, he found the crowd gathered, and when the disciples came to him he sat down, and delivered this sermon to the crowds and the disciples. And this seems truer: because Matthew says at the end of the sermon that the crowds marveled at his teaching. Nevertheless, whichever is accepted, there is no contrariety.”
Source

Post-Reformation

c. 1650 – 1900
1714
A.D.
Matthew Henry Reformed
1662–1714
“We have here a general account of this sermon. I. The Preacher was our Lord Jesus, the Prince of preachers, the great Prophet of his church, who came into the world, to be the Light of the world. The prophets and John had done virtuously in preaching, but Christ excelled them all. He is the eternal Wisdom, that lay in the bosom of the Father, before all worlds, and perfectly knew his will (Joh 1:18); and he is the eternal Word, by whom he has in these last days spoken to us. The many miraculous cures wrought by Christ in Galilee, which we read of in the close of the foregoing chapter, were intended to make way for this sermon, and to dispose people to receive instructions from one in whom there appeared so much of a divine power and goodness; and, probably, this sermon was the summary, or rehearsal, of what he had preached up and down in the synagogues of Galilee. His text was, Repent, for the kingdom of heaven is at hand. This is a sermon on the former part of that text, showing what it is to repent; it is to reform, both in judgment and practice; and here he tells us wherein, in answer to that question (Mal 3:7), Wherein shall we return? He afterward preached upon the latter part of the text, when, in divers parables, he showed what the kingdom of heaven is like, ch. 13. II. The place was a mountain in Galilee. As in other things, so in this, our Lord Jesus was but ill accommodated; he had no convenient place to preach in, any more than to lay his head on. While the scribes and Pharisees had Moses' chair to sit in, with all possible ease, honour, and state, and there corrupted the law; our Lord Jesus, the great Teacher of truth, is driven out to the desert, and finds no better a pulpit than a mountain can afford; and not one of the holy mountains neither, not one of the mountains of Zion, but a common mountain; by which Christ would intimate that there is no such distinguishing holiness of places now, under the gospel, as there was under the law; but that it is the will of God that men should pray and preach every where, any where, provided it be decent and convenient. Christ preached this sermon, which was an exposition of the law, upon a mountain, because upon a mountain the law was given; and this was also a solemn promulgation of the Christian law. But observe the difference: when the law was given, the Lord came down upon the mountain; now the Lord went up: then, he spoke in thunder and lightning; now, in a still small voice: then the people were ordered to keep their distance; now they are invited to draw near: a blessed change! If God's grace and goodness are (as they certainly are) his glory, then the glory of the gospel is the glory that excels, for grace and truth came by Jesus Christ, Co2 3:7; Heb 12:18, etc. It was foretold of Zebulun and Issachar, two of the tribes of Galilee (Deu 33:19), that they shall call the people to the mountain; to this mountain we are called, to learn to offer the sacrifices of righteousness. Now was this the mountain of the Lord, where he taught us his ways, Isa 2:2, Isa 2:3; Mic 4:1, Mic 4:2. III. The auditors were his disciples, who came unto him; came at his call, as appears by comparing Mar 3:13, Luk 6:13. To them he directed his speech, because they followed him for love and learning, while others attended him only for cures. He taught them, because they were willing to be taught (the meek will he teach his way); because they would understand what he taught, which to others was foolishness; and because they were to teach others; and it was therefore requisite that they should have a clear and distinct knowledge of these things themselves. The duties prescribed in this sermon were to be conscientiously performed by all those that would enter into that kingdom of heaven which they were sent to set up, with hope to have the benefit of it. But though this discourse was directed to the disciples, it was in the hearing of the multitude; for it is said (Mat 7:28), The people were astonished. No bounds were set about this mountain, to keep the people off, as were about mount Sinai (Exo 19:12); for, through Christ, we have access to God, not only to speak to him, but to hear from him. Nay, he had an eye to the multitude, in preaching this sermon. When the fame of his miracles had brought a vast crowd together, he took the opportunity of so great a confluence of people, to instruct them. Note, It is an encouragement to a faithful minister to cast the net of the gospel where there are a great many fishes, in hope that some will be caught. The sight of a multitude puts life into a preacher, which yet must arise from a desire of their profit, not his own praise. IV. The solemnity of his sermon is intimated in that word, when he was set. Christ preached many times occasionally, and by interlocutory discourses; but this was a set sermon, kathisantos autou, when he had placed himself so as to be best heard. He sat down as a Judge or Lawgiver. It intimates with what sedateness and composure of mind the things of God should be spoken and heard. He sat, that the scriptures might be fulfilled (Mal 3:3), He shall sit as a refiner, to purge away the dross, the corrupt doctrines of the sons of Levi. He sat as in the throne, judging right (Psa 9:4); for the word he spoke shall judge us. That phrase, He opened his mouth, is only a Hebrew periphrasis of speaking, as Job 3:1. Yet some think it intimates the solemnity of this discourse; the congregation being large, he raised his voice, and spoke louder than usual. He had spoken long by his servants the prophets, and opened their mouths (Eze 3:27; Eze 24:27; Eze 33:22); but now he opened his own, and spoke with freedom, as one having authority. One of the ancients has this remark upon it; Christ taught much without opening his mouth. that is, by his holy and exemplary life; nay, he taught, when, being led as a lamb to the slaughter, he opened not his mouth, but now he opened his mouth, and taught, that the scriptures might be fulfilled, Pro 8:1, Pro 8:2, Pro 8:6. Doth not wisdom cry - cry on the top of high places? And the opening of her lips shall be right things. He taught them, according to the promise (Isa 54:13), All thy children shall be taught of the Lord; for this purpose he had the tongue of the learned (Isa 50:4), and the Spirit of the Lord, Isa 61:1. He taught them, what was the evil they should abhor, and what was the good they should abide and abound in; for Christianity is not a matter of speculation, but is designed to regulate the temper of our minds and the tenour of our conversations; gospel-time is a time of reformation (Heb 9:10); and by the gospel we must be reformed, must be made good, must be made better. The truth, as it is in Jesus, is the truth which is according to godliness, Tit 1:1.”
1849
A.D.
1774–1849
“What is said here, does not follow immediately what was said in the preceding chapter. See Luke vi.”

Undated

date unknown
date
unknown
“Every man in his own trade or profession rejoices when he sees an opportunity of exercising it; the carpenter if he sees a goodly tree desires to have it to cut down to employ his skill on, and the Priest when he sees a full Church, his heart rejoices, he is glad of the occasion to teach. So the Lord seeing a great congregation of people was stirred to teach them.”
Source
“For as all other vices, but chiefly pride, casts down to hell; so all other virtues, but chiefly humility, conduct to Heaven; it is proper that he that humbles himself should be exalted.”
date
unknown
Glossa Ordinaria Medieval
“(interlin.) The riches of Heaven are suitably promised to those who at this present are in poverty.”
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.